Marijuana is the most prevalent illicit drug used by teenagers and adults around the world. Nearly a third of high school students in the United States report smoking it, and most high schoolers say they have access to the drug.

To many people, smoking pot is no big deal. They cite reasons such as: "it isn't dangerous or addictive" and "everybody is doing it."

Denise Walker, co-director of the University of Washington's Innovative Programs Research Group, disagrees.

"It's not a risk-free drug," she said. "Lots of people who use it do so without problems. But there are others who use it regularly – almost daily – and want to stop but aren't sure how."

Walker hopes to help these people, many of whom feel stigmatized by their drug use. She is lead author of a paper showing that a brief, voluntary conversation with an adult led to up to a 20 percent decrease in marijuana use for teenagers who frequently used the drug. The paper was published online June 20 in the journal Psychology of Addictive Behaviors.

Teenagers face greater risks from regular marijuana use compared with adults, said Walker, who is also a UW research assistant professor of social work.

"Adolescence is a big developmental period for learning adult roles. Smoking marijuana regularly can impede development and school performance, and it sets kids up for other risky behaviors," she said.

Walker and her co-authors investigated how a two-session, "non-finger wagging" approach called Teen Marijuana Check-Up could encourage teens to reduce their marijuana use.

"The majority of people who need help aren't getting it and they don't think they need it," Walker said. Users are ambivalent about their drug use, Walker reported, and there are aspects of using marijuana they enjoy.

"However, many teens also have concerns about their use, even if they're not sharing them with family or friends," she said. If a convenient and easy opportunity to weigh the pros and cons of their drug use is offered that isn't "shaming or blaming," kids will participate in it voluntarily, she said.

The researchers went to high school classrooms and gave short presentations describing myths and facts about marijuana, common reasons why teens smoke it and its health and behavior consequences.

The researchers told the students about the study, saying it was intended to give feedback on – not treat – each student's marijuana use. Students could volunteer privately. Of about 7,100 students who heard about the study, 619 volunteered and 310 met its criterion of smoking marijuana regularly.

The participants, ninth through 12th graders attending Seattle public schools, had two one-on-one meetings with health educators. During the meetings, which lasted 30-60 minutes each over two weeks, the health educators used one of two approaches:

  • Motivational interviewing, in which the health educator and student discussed the student's marijuana use and how it might be interfering with the student's life, goals and personal values, and the health educator told the student about social norms of how much others use the drug.
  • An educational approach in which a PowerPoint presentation described current marijuana research and health and psychological effects of marijuana use.

Participants in the motivational interviewing group started the study using marijuana 40 out of the previous 60 days. Three months after counseling they had decreased their use 20 percent, to 32 out of 60 days. After a year they still showed a 15 percent decrease, 34 days out of 60.

Participants in the educational treatment group had slower results, reporting an 8 percent decrease from 38 to 35 days out of 60 days three months after the treatment ended. A year later, they reported using marijuana 34 of 60 days, an 11 percent overall drop.

The researchers called the findings "encouraging in that apparently meaningful reductions in cannabis use resulting from the brief meetings were sustained over a relatively lengthy period of time."

Walker said that the low-burden, low-cost program could be disseminated to drug and alcohol counselors in schools. The program "is supposed to attract people who aren't ready for a full treatment, but are interested in having a conversation with a professional trained to discuss concerns with substance use," she said.